// MIT License
// 
// Copyright (c) 2021 Cong Feng
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package com.example.dataset;

import java.util.Map;
import java.io.IOException;
import java.util.HashMap;

// This is a singleton class. All KnnDatasets are returned by him.
public class KnnDatasetFactory {

    private Map<String, KnnDataset> nameToDataset = new HashMap<String, KnnDataset>();
    private static KnnDatasetFactory instance;

    private void registerKnownDatasets() {
        registerDataset("iris", new IrisDataset());
        registerDataset("car_owners", new CarOwnersDataset());
    }

    private KnnDatasetFactory() {
        registerKnownDatasets();
    }

    public static KnnDatasetFactory get() {
        if (instance == null) {
            instance = new KnnDatasetFactory();
        }
        return instance;
    }

    public KnnDataset getDataset(String name) throws IOException {
        KnnDataset ds = nameToDataset.get(name);
        if (ds == null) {
            throw new IOException(String.format("Invalid dataset name %s", name));
        }
        return ds;
    }

    public void registerDataset(String name, KnnDataset ds) {
        nameToDataset.put(name, ds);
    }
}
